Fn. Buchi et al., STUDY OF RADIATION-GRAFTED FEP-G-POLYSTYRENE MEMBRANES AS POLYMER ELECTROLYTES IN FUEL-CELLS, Electrochimica acta, 40(3), 1995, pp. 345-353
Proton exchange membranes for fuel cell applications were synthesized
by pre-irradiation grafting of styrene/divinylbenzene mixtures into po
ly(fluoroethylene-co-hexafluoropropylene) films and subsequent sulfona
tion. Grafting of pre-existing films overcomes the problem of shaping
the grafted polymer into thin membranes and makes this process a poten
tially cheap and easy technique for the preparation of solid polymer e
lectrolytes. The grafted membranes were characterized by measuring the
ir ion exchange capacity, swelling, specific resistivity and area resi
stance. Due to their thickness in the range 67-211 mu m, some of the m
embranes have a considerably lower resistance than the most widely use
d membrane Nafion(R) 117 (DuPont). The short-term and long-term perfor
mance of these membranes was investigated in H-2/O-2 fuel cells. Thin
(< 100 mu m), highly crosslinked (12% divinylbenzene) membranes show t
he best performance in the fuel cells. Tests for periods of up to 1400
h were performed to examine membrane stability and the degradation of
grafted membranes.